This invention relates to a magnetic separator for, and a method of, magnetically separating magnetisable particles from a fluid.
A conventional magnetic separator generally comprises a separating region containing a magnetisable packing material which, in operation, is magnetised by the application of a magnetic field to provide a large number of "collecting sites" of high magnetic field intensity within the packing material. In use of the separator, a feed suspension of magnetisable and substantially non-magnetisable particles in a fluid is introduced into the packing material. A large proportion of the magnetisable particles of the suspension are magnetised and attracted to the collecting sites, whilst the bulk of the substantially non-magnetisable particles pass out of the packing material. The magnetisable particles entrained in the packing material are subsequently removed externally of the magnetic field.
British Pat. No. 1,054,807 (G.H. Jones) describes and claims a rotary magnetic separator for separating solid magnetisable particles from a fluid in which they are suspended, the separator including a stator comprising a plurality of pairs of poles arranged in alternate polarity around the stator so as to provide alternate zones of strong and weak or zero magnetic field, a rotor having a plurality of gaps between walls made of magnetisable material, said rotor being adapted to rotate about a vertical axis such that any part of the rotor will pass through alternate zones of strong and weak or zero magnetic field on rotation, means for feeding the particle carrying fluid into the upper ends of the gaps in zones of strong magnetic field, means for collecting the fluid which has passed through the gaps, means for feeding rinsing fluid through the gaps whilst they are still within zones of strong magnetic field so that any non-magnetic particles adhering to the walls are washed off, and means for directing flushing fluid through the gaps in zones of weak or zero magnetic field such that the magnetic particles are removed from the walls of the gaps.
U.S. Pat. No. 3,375,925 (Carpenter) describes and claims a magnetic separator for separating granular materials of differing magnetic susceptibility comprising:
at least one magnet means having oppositely disposed field poles of opposite polarity for producing an effective magnetic field therebetween;
a plurality of loose, unattached induced pole pieces, said induced pole pieces being individually means for carrying and retaining the induced pole pieces, movable relative to each other;
means for moving the induced pole pieces and the field poles relative to each other so that the induced pole pieces pass into, through and out of the effective magnetic field;
means for introducing the material to be separated into the effective magnetic field and therein into proximity with the induced pole pieces as the pieces pass through the field; and
means for flushing material from proximity with the induced pole pieces after the pieces have passed out of the effective magnetic field.
In all the embodiments described, the feed material is allowed to fall by gravity into an open-topped box containing the induced pole pieces and the product and waste streams flow through the open bottom of the box into suitable receiving launders.